It is common surgical practice to use bypass grafts to help reestablish coronary artery circulation. In most patients one or usually more segments of the saphenous vein taken from the patient's legs will be implanted between the aorta near its base and just distal to the blockage of the branch of the stenosed coronary artery. In some patients, the internal mammary artery is also utilized for bypassing the most important coronary artery which is stenosed.
The aorta is cross clamped during the period of actual coronary artery surgery to minimize bleeding from the anastomotic sites of the coronary arteries. However, when an incision is made into the stenotic coronary artery, sometimes a significant amount of hemorrhage occurs. The hemorrhage is thought to be due to the presence of collateral circulatory channels, probably emanating from the bronchial arteries. In such circumstances the surgeon's delicate task of producing a competent, yet leak tight, anastomosis between the bypass graft and the semi-occluded vessel in a resonably short time, is made difficult.
The coronary artery occluder, which is the subject of this invention, is intended for use as an aid to the surgeon in this particular circumstance by preventing or minimizing hemorrhage from the coronary arteries during this procedure. The device serves to occlude the artery to minimize bleeding.
Vessel occluders are known in the art. For example Mullen, D. C., Lepley, D. Jr., and Flemma, R. J. described the use of a coronary occluder in their paper "Coronary artery surgery without global ischemia." Ann Thorac Surg 24:90, 1977. This device is a "T" shaped device with a bulbous tip placed at either end of the "T." The device was manufactured from silicon rubber.
A similar device, the Florester.RTM. coronary artery occluder, is presently produced, and described in a brochure, by Bio-Vascular, Inc. St Paul, Minnesota. The drawback of this device is that it is expensive and is intended for multiple use. Following each use the device has to be thoroughly cleansed and re-sterilized before reuse in the next patient. The "T" configuration in which the bulbous tips are placed at opposite ends of the "T" can also cause difficulties for the surgeon. The bulbous tips of the device have to be inserted into each of the two parts of the vessel a cumulative amount equal to the distance between the tips, this distance being fixed by the configuration of the device. Normally each tip would be inserted an equal distance into the vessel, but should the anastomotic site be close to a proximal partial coronary occlusion, one tip can only be inserted a short distance before reaching the occlusive area. It follows, in such circumstances, that the second tip, being a fixed distance from the first, will have to be inserted further into the distal coronary artery than desired. Should a bifurcation be present within this distance the device could not be used. A further disadvantage of the device is that the core material of the "T" is of braided fibers coated with silicon rubber. Should the surgeon inadvertently catch and penetrate this with the suture needle the device is permanently damaged and has to be discarded.
Similar devices could be manufactured by the injection molding of a suitable thermoplastic material onto a suitable flexible suture, preferably of monofilament construction. The drawback of this approach is that while of low cost, injection molding dies involve parting or split lines in the dies, which cause "flash" on the molded parts. This "flash" takes the form of surface discontinuities, which would have to be removed before the device could safely be inserted into the lumen of a coronary artery. The removal of "molding flash" could be expensive and difficult. Any significant surface blemish on the coronary occluder would potentially cause trauma to the intima of the vessel, leading to coronary thrombosis. The device which is the subject of this invention does not have these disadvantages.
It is an objective of this invention to provide a vessel occluder which overcomes the described deficiencies in the prior art.
It is a further objective of this invention to provide a vessel occluder without significant surface defects on the vessel intima contacting surfaces.
It is a further objective of this invention to temporarily hold open the arteries during anastomosis to improve exposure of the cut ends of the vessel for the anastomosis.
It is a further objective of this invention to occlude the artery to minimize bleeding.
It is a further objective of this invention to provide a vessel occluder to occlude coronary arteries.
It is a further objective of this invention to provide a vessel occluder with bulbous tips that do not have to be inserted into the vessel a predetermined cumulative distance.
It is a further objective of this invention to provide a vessel occluder with bulbous tips connected and retailed with a monofilament member.
The simplicity and design of the vessel occluder of this invention are such that it is quite inexpensive and hence may be disposable, hereby eliminating the necessity of cleaning and sterilizing between uses. Other objectives and advantages of this invention will be more apparent from the detailed description of the device which follows.